KR20150090180A - Apodization for pupil imaging scatterometry - Google Patents

Abstract

The present invention relates to various apodization methods for measuring the pupil-forming scattering rate. In some embodiments, the system includes an apodizer disposed in the pupil plane of the illumination path. In some embodiments, the system also includes an illumination scanner configured to scan the surface of the sample by at least a portion of the apodized illumination. In some embodiments, the system includes an apodized pupil configured to provide a quadrupole illumination function. In some embodiments, the system also includes an apodized collection field aperture. The various embodiments described herein may be combined to achieve certain advantages.

Description

[0002] APODIZATION FOR PUPIL IMAGING SCATTEROMETRY [0003]

preference

This application is a continuation-in-part of application filed on November 27, 2012, entitled " Apodization for Measuring Pupillary Imaging Rate " by Andy Hill et al. United States Patent No. 61 / 730,383, which is an applicant for benefit, claims priority. Such a patent application is hereby incorporated herein by reference in its entirety.

Technical field

The present invention relates generally to the field of optical metrology, and more particularly to apodization of optical metrology systems.

Optical metrology is sometimes utilized to measure the optical and / or structural characteristics of a device or test feature during semiconductor fabrication. For example, optical or structural properties may include critical dimensions such as height, sidewall angle, pitch, line width, film thickness, refractive index, and overlay between exposures within or between different layers. Apodization can be implemented in an optical metrology system to control the angle and spatial distribution of illumination at well-defined locations along the optical path. Apodization is especially important when the measurement accuracy and precision are dependent on the ability to search for spectral or angular information with high fidelity from a metrology target that is small. In such a case, there is a need to prevent signal contamination due to unwanted scattering from the designated measurement target outer region in the sample, or due to scattering from the intermediate optical component or aperture along the optical path.

In the case of an angle analysis type (pupil imaging) scatterometer, the practice known in the art is: (1) numerical aperture (NA) so that different diffraction orders from the measurement target can be separated from the collection pupil; (Pupil) diaphragm in the illumination path that confines the pupil of the pupil; (2) a combination of a simple top planar field-of-view aperture in the illumination path to focus the light onto a small target. With this structure, the illumination field stop becomes a limiting aperture of the pupil imaging system. The hard edge of the illumination field aperture causes ringing in the image of the illumination aperture, which is the interaction between the orders in the pupil image (e.g., zero order and first order) or Causing interference. One way to solve this problem is field apodization in the illumination path of an optical metrology system. By this field apodization, the introduction of a smoothly varying transmission function in the field of vision results in a smooth changing and rapidly decaying function in the conjugate pupil plane, effectively suppressing the ringing which causes inter-order interference.

The approach described above may be appropriate for a spatially incoherent system with illumination etendue for a spare. However, in the case of optical metrology systems that use coherent illumination sources, such as laser based systems with high spatial and temporal coherence, substantial noise problems arise. Shaping the spatial coherent illumination beam to have a low tail in the field plane is desirable to minimize ambient contamination and diffraction by the edge of the target. The low tail at the pupil plane is desirable to minimize interference and interference between clipping and diffraction orders by the objective pupil. The beam can be potentially shaped by some coupling amplitude and phase apodization in the illumination field aperture or illumination aperture. In order to average the effect of the target noise, it is desirable to scan the spatially coherent illumination spot on the target during the measurement. If beam shaping is performed in the illumination viewing plane and the spot scanning mechanism is positioned in front of the viewing plane, the beam shape at the viewing and pupil plane will change when spot scanning is performed across the viewing apodizer . This causes not only the variation of the total beam intensity but also the asymmetry of the light distribution in the pupil.

The present invention relates to healing some or all of the aforementioned defects known in the art using one or more of the apodization schemes described below.

Various embodiments of the present invention relate to a system for performing optical metrology comprising at least one illumination source configured to illuminate a sample and at least one detector configured to receive at least a portion of the illumination scattered, do. The at least one computing system communicatively coupled to the one or more detectors may be configured to determine at least one spatial attribute of the sample, such as an optical or structural characteristic, based on a portion of the detected illumination.

The system may include an apodizer or an apodized pupil disposed in the pupil plane of the illumination path. The apodizer can be configured to apodize illumination directed along the illumination path. In some embodiments, the system may also include an illumination scanner configured to scan the surface of the sample by at least a portion of the apodized illumination disposed along the illumination path. The system also includes an illumination field stop configured to block a portion of the illumination directed along the illumination path from scanning the sample surface and a collection field aperture configured to block a portion of the illumination directed along the collection path from being received by the detector can do.

In some embodiments, the system may include apodized pores disposed along the illumination path. The apodized pupil may include at least four elongated apertures configured to provide a quadrupole illumination function. The apodized pupil can also be configured to apodize directed illumination along the illumination path. Further, the illumination field diaphragm disposed along the illumination path can be configured to block a portion of the illumination directed along the illumination path from striking the surface of the sample or scanning the surface of the sample.

In some embodiments, the system may also include an apodized collection field aperture that includes an apodizer disposed in the pupil plane of the illumination path and is disposed along the collection path. The apodized acquisition field aperture is configured to apodize directed illumination along the collection path and may also be configured to block a portion of the illumination directed along the collection path from being received by the detector.

It will be appreciated by those skilled in the art that the foregoing embodiments and the additional embodiments described below may be combined to achieve various advantages. Accordingly, the configurations described herein should not be construed as limiting the invention unless otherwise indicated. It is also to be understood that the foregoing general description and the following detailed description are exemplary and are not necessarily limitations of the invention. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the subject matter of the present invention. The description and drawings herein together serve to illustrate the principles of the invention.

Many of the advantages of the present invention can be better understood by those skilled in the art by reference to the accompanying drawings.
1 is a block diagram showing an optical metrology system including an apodizer arranged in a pupil plane of a system according to an embodiment of the present invention.
2 is a block diagram illustrating an optical metrology system further comprising an illumination scanner disposed within a pupil plane of the system, in accordance with an embodiment of the present invention.
3 is a block diagram illustrating an optical metrology system in which an illumination scanner is disposed behind an illumination field aperture, in accordance with an embodiment of the present invention.
4 is a block diagram showing an optical metrology system including an apodized illumination field diaphragm, in accordance with an embodiment of the present invention.
5 is a block diagram illustrating an optical metrology system disposed behind an apodi-dim illumination field-of-view and illumination scanner, in accordance with an embodiment of the present invention.
6 is a block diagram showing an optical metrology system in which an apodizer and an illuminated field aperture are disposed behind an illumination scanner, in accordance with an embodiment of the present invention.
Figure 7 is a block diagram showing an optical metrology system further comprising an apodized collection field diaphragm, in accordance with an embodiment of the present invention.
8 is a block diagram illustrating an optical metrology system configured to illuminate illumination along a sample surface and configured to de-scan illumination collected from a sample surface, according to an embodiment of the present invention.
9A is a graphical illustration of an exemplary apodizer scalar pupil plane profile, in accordance with an embodiment of the present invention.
9B is a graphical representation of the wafer plane scalar intensity (logarithmic scale) for an exemplary apodizer scalar pupil plane profile, in accordance with an embodiment of the present invention.
9C is a graphical representation of a resulting scalar profile in a pupil image sensor (i.e., detector) plane for an exemplary apodizer scalar pupil plane profile, in accordance with an embodiment of the present invention.
10A is a view showing a pupil configured for a quadrupole illumination function according to an embodiment of the present invention.
Fig. 10B is a diagram showing a plurality of pupil constructions according to the embodiment of the present invention. Fig.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, embodiments of the present invention shown in the accompanying drawings will be described in detail.

Figures 1 to 10B schematically illustrate the apodization method of an optical metrology system 100 such as an angle analysis type (pupil imaging) scattering system. According to various embodiments, apodization in the pupil and / or detector plane enables high performance metrology in targets with relatively small dimensions. The following embodiments also include configurations relating to certain advantages in measurement quality, performance and / or accuracy. It is noted that the embodiments described below are used for illustrative purposes and that various portions of the embodiments may be combined to achieve additional embodiments with selected advantages.

In general, the following embodiments relate to one or more of the following advantages. Embodiments of the system 100 may include configurations that shape the illumination directed along the illumination path to avoid illuminating outside the target area of the measurement sample 102, such as a semiconductor wafer or mask. Embodiments of the system 100 may also include configurations for alleviating or eliminating diffracted or scattered illumination from the optical surface and / or the aperture edge along the illumination path to avoid pupil area contamination. Embodiments of the system 100 may also include a configuration for forming or excluding stray illumination reflected, scattered, or copied along the collection path to avoid illumination detection from areas outside the target area of the sample 102 . For example, some configurations may involve blocking or excluding an illuminated portion diffracted from an objective lens or a collection field aperture. Additional objectives or advantages are described below with respect to the following system 100 embodiments.

As shown in Figure 1, the system 100 includes at least one spatially coherent (e.g., laser) or non-coherent (e.g., laser sustained plasma (LSP) a laser driven light source (LDLS)). While some embodiments herein relate to an optical metrology system based on spatially interfering illumination sources, many of the advantages provided by the arrangements described herein are also applicable to systems based on spatially non-intrusive illumination sources . In some embodiments, the illumination source 104 may be configured to provide illumination along an optical fiber 106 that is directed to a free-space illumination path.

In some embodiments, the system 100 includes apodizer 108, such as a self-contained apodization element or apodized pupil disposed within the pupil plane of the illumination path. The system 100 may also include an illumination field stop 112 disposed along the illumination path. The illumination field stop 112 may be configured to focus the illumination on a target area of the sample 102 and block a portion of the illumination directed along the illumination path to filter out parasitic (scattered or diffracted) have.

In some embodiments, the system 100 also includes an illumination scanner 110, such as a scanning mirror, disposed between the apodizer 108 and the illumination field diaphragm 112. For example, the illumination optics may be configured such that illumination from the illumination source 104 is directed through the apodizer 108 and then scanned by the illumination scanner 110 across the illumination field aperture 112 Lt; / RTI > 5, the illumination optics are configured such that the illumination from the illumination source 104 is directed through the illumination field diaphragm 112 and then illuminated by the illumination scanner 110 to the apodizer 108 As shown in FIG. The illumination scanner 110 may include one or more actuators that cause the illumination scanner 110 to spot scan a target area of the sample 102 with additional shaped illumination along the viewing aperture 112 And can be coupled to such an actuator. The illumination optics may also be arranged such that the illumination scanner 110 is disposed within the pupil plane. For example, as shown in FIG. 2, the illumination scanner 110 may be conjugated to the pupil plane. The stability of the apodization function provided by the apodizer 108 during dot scans of at least a portion of the apodized illumination in the target area of the sample 102 may be improved by placing the illumination scanner 110 in the pupil plane .

In some embodiments, the apodizer 108 and illumination field diaphragm 112 are positioned in front of the illumination scanner 110, as shown in FIG. So that the illumination received by the illumination scanner 110 is apodized and further shaped according to the illumination field stop 112. With this arrangement, the illumination field stop 112 can include a smaller aperture, since illumination does not need to be scanned across the field stop 112. Therefore, the illumination field stop 112 can filter more of the spatial noise caused by the apodizer 108 and the optical fiber 106. [ In addition, there is less chance of introducing intensity noise caused by the time dependence of the diffraction at the point off the edge of the illumination field stop 112. When the illumination scanner 110 is disposed behind the apodizer 108 and the illumination field stop 112, strong diffraction due to scanning of the field aperture edge can be avoided.

FIG. 4 shows another embodiment in which the illumination field stop 112 can also be apodized to introduce a field of view apodization in addition to the pupil apodization provided by the pupil apodizer 108. The apodized illumination field diaphragm 112 may improve the ability to shape the illumination directed along the illumination path. The intensity modulation and change for the pupil distribution can occur during point scanning, but the diffraction effect due to the point reaching the edge of the illumination field stop 112 can be greatly alleviated by apodization. Reduction of the diffraction effect is important because, if not controlled, mixing of pupil points can occur. Since the image at the illumination field stop 112 is ultimately imaged on the sample 102, the field of view obdodation adds the spot intensity at the edge of the target area of the sample 102 and at the edge of the acquisition field aperture 120 , Thereby suppressing the mixing of pupil points in the collected pupil.

5 is a schematic diagram of the illumination optics 102 to direct illumination from the illumination source 104 through the illumination field stop 112 and then to be scanned across the apodizer 108 by the illumination scanner 110. [ And the apparatus is arranged. This arrangement allows a relatively small illumination field stop 112 to be placed in front of the illumination scanner 110 to reduce the input noise from the illumination source 104 and / or the optical fiber 106. Also, placing the apodizer 108 behind the illumination scanner 110 can increase the ability to shape the illumination being scanned across the sample 102. [

Alternatively, as shown in FIG. 6, an apodizer 108 and an illumination field diaphragm 112 may be positioned behind the illumination scanner 110. Placing the apodizer 108 behind the illumination scanner 110 allows for the stationary apodization function in the illumination pupil because the illumination scanner 110 only affects the angle of illumination through the apodizer 108 It becomes. The illumination field diaphragm 112 disposed behind the apodizer 108 also includes an apodizer 108, an illumination scanner 110, an optical fiber 106, and any additional illumination optics (e.g., Lens) can be filtered out and removed from the upstream component.

The system 100 may also include a beam splitter 114 configured to direct illumination from the illumination path through the objective lens 116 to illuminate the sample 102. [ The system 100 may include a stage 118 configured to support the sample 102. In some embodiments, the stage 118 may further include at least one actuator or may be coupled to such an actuator. The actuator may be configured to vary or rotate the stage 118 to position the sample 102 at a selected location. Thus, the illumination can be targeted or scanned in a selected area of the sample 102 by operation of the sample stage 118. Alternatively or additionally, one or more illumination optics, such as the objective lens 116, may be activated to target a selected area of the sample 102 and / or adjust the focus of the targeted illumination on the sample 102 .

The illumination may be scattered, reflected, or copied by a targeted area of the sample 102. The system 100 may include at least one detector 122 such as a camera, a scatterometer, a photodiode, or any other optical detector configured to receive at least a portion of the scattered, reflected, or copied illumination from the sample 102 have. In some embodiments, the acquisition field diaphragm 120 is coupled to a detector (not shown) to filter the parasitic illumination, such as illumination diffracted or scattered by the beam splitter 114, the objective lens 116 and / 122 to block at least a portion of the illumination directed from the sample 102 along the collection path.

In some embodiments, the acquisition field diaphragm 120 may be further apodized as shown in FIG. It is noted that among other features, particularly including the apodized acquisition field diaphragm 120, may be supported by any of the embodiments described herein. The apodized acquisition field stop 120 is used to determine the decentering error of the beam position in relation to the center of the target area of the sample 102 caused by diffraction or scattering from the edge of the acquisition field stop 120, Which is advantageous in decreasing the sensitivity to < RTI ID = 0.0 > In particular, collection field diaphragms with small numerical apertures (NA) are more sensitive to decentration errors and therefore can benefit greatly from apodization. For further explanation, the sensitivity to decentration can be determined from the desired diffraction (e.g., first order diffraction) from a predetermined order scattered from the field stop 120 and unwanted diffraction from other orders (e.g., Diffraction). ≪ / RTI > Interference between diffraction orders can be suppressed by acquisition field aperture apodization by shaping the illumination to compensate for diffraction or scattering effects. In addition, apodization of the collection field stop 120 can reduce the diffraction or scattering effect from the edge of the pupil aperture in the pupil plane positioned behind the collection field stop 120. By suppressing parasitic (diffracted or scattered) illumination from reaching the detector 122, it is possible to reduce the inaccuracies caused by decentering errors, thereby improving the measurement performance and further enhancing the accuracy.

The system 100 may include at least one computing system 124 communicatively coupled to one or more detectors 122. The computing system 124 may be configured to determine at least one spatial property of the sample 102 based on a detected portion of the scattered, reflected, or copied illumination from a target region of the sample 102. For example, the computing system 124 may be configured to determine the optical or structural characteristics of the sample 102 or the defect information associated with the sample 102 according to one or more of the metrology and / or inspection algorithms known in the art have. The computer system 124 may be configured to execute an inspection algorithm or at least one measurement embedded in the program instructions 128 stored by the at least one carrier medium 126 that is communicatively coupled. In some embodiments, computing system 124 includes at least one single-core or multi-core processor configured to execute program instructions 128 from a carrier medium 126 that is communicatively coupled. It should also be understood that any of the various steps or functions described throughout this specification may be performed by a single computing system or by multiple computing systems.

Figure 8 shows another embodiment of a system 100 in which the illumination scanner 110 is disposed along a portion of an illumination path and a portion of a collection path. Thus, the illumination scanner 110 points-scans the target area of the sample 102 by illumination transmitted along the illumination path, and also scans, reflects, or transmits the sample 102 from the sample 102 along the collection path to the detector 122 And may be configured to de-scan the illumination. By scanning and descanning each of the targeted illumination and the illumination collected from the sample 102 onto the sample 102, the illumination scanner 110 reduces the decentration error and improves the uniformity of the illumination received at the detector 122 can do. Therefore, the scan / descanning optics can improve the measurement performance.

The use of apodization in a pupil imaging scattering system is in part described in U.S. Patent Publication No. 20080037134, the contents of which are incorporated herein by reference. The apodizer 108, and in various embodiments the apodized illumination field stop 112 and / or the apodized collection field stop 120 may be any apoperator described in the aforementioned US Patent Publication No. 20080037134, It is possible to integrate the diode technology. One key characteristic of the apodizer is its transmission profile as a function of radial dimension. The apodization function sometimes has a trapezoidal or Gaussian shape. In some embodiments of system 100, the apodization profile may also include top hat, optimized top hat, Gaussian, hyperbolic tangent, or Blackman forms, for non-limiting examples . The 2D apodization distribution can also be implemented in Cartesian form by multiplying the 1D apodization distribution in the X direction and the corresponding 1D apodization distribution in the Y direction, instead of the polar-shaped apodization profile. As discussed further below, the apodization profile may be selected according to a cost function to improve or optimize system performance.

Figures 9A-9C show examples of scalar distributions for a number of different apodization profiles and corresponding resultant profiles at the sample imaging surface and the collection pupil surface. For example, FIG. 9A shows an example of a scalar pupil plane profile (transmission versus pupil coordinates) of a top hat, an optimized top hat, a Gaussian, and a hyperbolic tangent profile. Figure 9B shows the scalar intensity at the sample imaging plane corresponding to an exemplary apodization profile, and Figure 9C shows the corresponding resulting scalar profile at the detector (i.e., collection) pupil plane. There is a significant reduction in intensity around the illumination point of the sample coordinate, as shown by the exemplary illustration in Figures 9A-9C, thereby reducing signal contamination at the detector 122 from the area outside the target area of the sample 102 .

In some embodiments, the apodization profile may be selected according to a cost function. For example, the apodization profile can be specified to substantially maximize the tail-to-peak ratio at a given position in the aperture of the pupil detector 122 while substantially minimizing the overall signal and subsequent precision impulse. In the case of 1D, the pupil apodization profile can be selected according to the following cost function.

Where p 0 (k) is the pupil apodizer profile, x ₀ defines the target range of the sample, k ₀ defines the target range of the pupil plane, and λ ₁ is the pupil diameter of the pupil plane and pupil function uniformity. Defines the relative weight of the tail reduction, and NA defines the pupil opening (natural unit). Also, in an embodiment, the acquisition apodization profile may be selected according to the following cost function.

Here, p (x) is the field of view Apo die low profile, x ₁ is and defining a target area of the sample, k ₀ is defined a target area on the pupil plane and, λ ₂ is a view side and a collection field stop function uniformity Lt; RTI ID = 0.0 > L < / RTI > defines the acquisition field aperture size.

In some embodiments, the illumination spectrum can be changed as part of the calibration recipe setup. For example, the illumination spectrum may be controlled using a spectral controller or a spatial light modulator (SLM), such as a DLP micromirror array manufactured by Texas Instruments. For example, an apodization profile may be determined and used by a target-related parameter such as size, pitch, or reflectance as a function of wavelength, along with a similar property of target proximity, according to a cost function similar to the apodization profile selection cost function described above. Lt; / RTI >

Despite the advantages of a strong apodization function, there may be associated signal loss and resulting measurement accuracy loss. In some embodiments, the shape of the pupil, and thus the pupil function, can be modified to recalibrate the measurement accuracy. FIGS. 10A and 10B show various pupil functions 200 that can be applied to the apodized pupil 108. FIG. In some embodiments, as shown in FIG. 10A, spots (pupil apertures) 202a-202d may extend in a direction orthogonal to the diffraction to increase the size of the diffraction spot. In addition, the apodized pores 200 are arranged such that the extensions are always in a direction orthogonal to the diffraction, and that 4 (including 4 at least four elongated apertures 202a-202d) to order from the ratio of the higher illumination wavelength to the lattice pitch It can be configured for pole lighting. A further embodiment of the pupil 200 is shown in FIG. 10B. However, it is expected that various modifications can be made without departing from the scope of the present invention.

Although some embodiments described so far are related to intensity-only modulated apodization functions, it is noted that the apodization function may be a complex function that combines intensity modulation with phase apodization. For example, the cost functions p (x) and p (k) presented above for visual field and pupil apodization can be rewritten to p = | p | e ^iψ , where | p | Lt; RTI ID = 0.0 > phase modulation. ≪ / RTI >

The apodization element can be made by several techniques known in the art. Some examples include a halftone amplitude transmission mask, a varying neutral density mask, and a phase modulation mask. Lithographic techniques are known to work particularly well for phase masks with halftone amplitude masks and discrete phase steps (e.g., about 8 levels). In some embodiments, the apodization element can be made using a standard electron beam recording technique on a resist on a photomask blank to produce the required high precision apodization for the optical metrology system 100.

Although the embodiments described above and shown in the drawings show a single optical column (i.e., a single line illumination path and a single line collection path), one skilled in the art will recognize that multiple paths may exist in one optical column I will understand. For example, multipath optics can be used in different illumination and collecting polarization states as described in U.S. Patent Publication No. 2011000108892. The contents of which are incorporated herein by reference. In some embodiments, two or more polarizing paths may be simultaneously apodized by a cavity apodizer, and there may be a separate apodilane for each polarization path.

The combination of apodization and scanning beam can provide significant advantages. The scanning of the spatially interfering beam allows the illumination spot size to be controlled for each target without loss of light that alters the imaged field aperture size. Systems that support spatial coherent illumination enable the smallest possible spot on the target and consequently the smallest possible target size. In addition, apodization of pupil function (as opposed to field of view) allows the critical distribution to be stably maintained in the illumination pupil during point injection. It is also noted that the scanning module may be utilized to induce intensity modulation in the illumination illuminated from the source. Thus, the incident spot on the sample may have a wafer coordinate dependent total intensity. This enables an illumination field diaphragm that is effectively apodized to the incoherent light source. An important advantage of this combination is that flexibility in selecting the apodization function is improved. In addition, an illumination field apodiable which does not cause scattering side effects due to the manufacturing process is obtained.

Additional advantages of the foregoing embodiments include, but are not limited to, reducing or eliminating signal contamination in the collecting pupil from scattered light from outside the target area; Reduction or elimination of signal contamination in the collection pupil from scattered light from apertures along the illumination or collection optical path; A stable illumination pupil distribution during point scanning; Reducing the interaction between the spot and field aperture and the target edge during scanning; And controlled scans that enable a tradeoff between peripheral interaction or edge diffraction and better target noise averaging.

(E. G., Hardware, software and / or firmware) enabling the processes and / or systems and / or other techniques described herein to be performed by those skilled in the art, Systems and / or other technologies are deployed. Program instructions that implement methods such as those described herein may be transmitted over a carrier medium or stored on a carrier medium. Carrier media include transmission media such as wires, cables, or wireless transmission links. The carrier medium may also include a read only memory, a random access memory, a magnetic disk or an optical disk, or a storage medium such as a magnetic tape.

All of the methods described herein may include storing results of one or more steps of a method embodiment in a storage medium. The results may include any results described herein, and may be stored in any manner known in the art. The storage medium may include any storage medium described herein or any other suitable storage medium known in the art. After the results are stored, the results can be accessed in a storage medium and used by any method or system embodiment described herein, or formatted for display to a user, or used by other software modules, methods or systems, . Further, the results may be stored "permanently", "semi-permanently", temporarily, or for a predetermined period of time. For example, the storage medium may be a random access memory (RAM), and the results need not necessarily last indefinitely in the storage medium.

Although specific embodiments of the present invention have been described so far, it will be apparent to those skilled in the art that various modifications and embodiments of the present invention can be made without departing from the scope and spirit of the foregoing description. Accordingly, the scope of the invention should be limited only by the claims appended hereto.

Claims (30)

A system for performing optical metrology,
A stage configured to support a sample;
At least one illumination source configured to provide illumination along an illumination path;
An apodizer disposed in a pupil plane of the illumination path and configured to apodize illumination directed along the illumination path;
An illumination scanner disposed along the illumination path and configured to scan a surface of the sample with at least a portion of the apodized illumination;
An illumination field stop disposed along the illumination path and configured to block a portion of the illumination directed along the illumination path from scanning the surface of the sample;
At least one detector configured to detect a portion of the scattered, reflected, or copied illumination from the surface of the sample along a collection path;
A collection field stop disposed along the collection path and configured to block a portion of the directed illumination along the collection path from being detected;
A computing system communicatively coupled to the at least one detector and configured to determine at least one spatial attribute of the sample based on a portion of the detected illumination. The optical metrology performing system according to claim 1, wherein the illumination scanner is disposed on a pupil plane of the illumination path. 2. The system of claim 1, wherein the illumination scanner is disposed along the illumination path between the apodizer and the illumination field diaphragm. 4. The system of claim 3, wherein the apodizer is disposed between the at least one illumination source and the illumination scanner. 4. The system of claim 3, wherein the illumination field diaphragm is disposed between the at least one illumination source and the illumination scanner. 2. The system of claim 1, wherein the illumination field diaphragm is disposed along the illumination path between the apodizer and the illumination scanner. 2. The system of claim 1, wherein the apodizer is disposed along the illumination path between the illumination scanner and the illumination field diaphragm. 2. The system of claim 1, wherein the illumination field diaphragm comprises an apodized field stop. 2. The system of claim 1, wherein the illumination scanner is further configured to direct illumination, scattered, reflected or copied from the surface of the sample along the collection path, to the at least one detector. 2. The system of claim 1, wherein the at least one illumination source comprises a coherent illumination source. 2. The method of claim 1, wherein the apodization profile of the apodizer is expressed by the following equation

, Where < RTI ID = 0.0 >
F (p (k)) is a cost function,
p (k) is the pupil apodizer profile,
x ₀ defines the target range of the sample,
k ₀ defines a target range of the pupil plane,
lambda ₁ defines the relative weight of the tail reduction in the field plane and pupil function uniformity,
And NA defines a pupil aperture. 2. The system of claim 1, wherein the acquisition field diaphragm comprises an apodized field diaphragm configured to apodize directed illumination along the collection path. 13. The method of claim 12, wherein the apodization profile of the apodized collected field aperture has the following formula:

, Where < RTI ID = 0.0 >
F (p (x)) is a cost function,
p (x) is the field aperture apodizer profile,
x ₀ defines the target range of the sample,
k ₀ defines a target range of the pupil plane,
lambda ₂ defines the relative weight of the tail reduction in the field of view and in the acquisition field aperture irregularity uniformity,
L < / RTI > defines a viewing aperture size. 2. The system of claim 1, further comprising a spectral controller disposed along the illumination path and configured to influence apodization by controlling a spectrum of illumination directed along the illumination path. 15. The system of claim 14, wherein the spectral controller comprises a micromirror array, a plurality of active shutters, or a selected filter. A system for performing optical metrology,
A stage configured to support a sample;
At least one illumination source configured to provide illumination along an illumination path to illuminate a surface of the sample;
And at least four elongated apertures disposed along the illumination path and configured to provide a quadrupole illumination function and configured to apodize illumination directed along the illumination path, An apodized pupil;
An illumination field stop disposed along the illumination path and configured to block a portion of the illumination directed along the illumination path from striking the surface of the sample;
At least one detector configured to detect a portion of the scattered, reflected, or copied illumination from the surface of the sample along a collection path;
A computing system communicatively coupled to the at least one detector and configured to determine at least one spatial property of the sample based on a portion of the detected illumination. 17. The system of claim 16, further comprising an illumination scanner disposed along the illumination path and configured to scan a surface of the sample with at least a portion of the apodized illumination. 18. The system of claim 17, wherein the illumination scanner is further configured to direct illumination, scattered, reflected or copied from a surface of the sample along the collection path, to the at least one detector. 17. The system of claim 16, wherein the illumination field diaphragm comprises an apodized field stop. 17. The system of claim 16, wherein the at least one illumination source comprises a coherent illumination source. 17. The method of claim 16, wherein the apodization profile of the apodized pupil is determined by the following equation:

, Where < RTI ID = 0.0 >
F (p (k)) is a cost function,
p (k) is the pupil apodizer profile,
x ₀ defines the target range of the sample,
k ₀ defines a target range of the pupil plane,
lambda ₂ defines the relative weight of the tail reduction in the field plane and pupil function uniformity,
And NA defines a pupil aperture. 17. The apparatus of claim 16, further configured to apodize illumination directed along the collection path, disposed along the collection path, and configured to block a portion of the illumination directed along the collection path from being detected Further comprising an acquired collection field stop. ≪ Desc / Clms Page number 17 > 23. The method of claim 22, wherein the apodization profile of the apodized collected field aperture has the following formula:

, Where < RTI ID = 0.0 >
F (p (x)) is a cost function,
p (x) is the field stop apodizer profile,
x ₀ defines the target range of the sample,
k ₀ defines a target range of the pupil plane,
lambda ₂ defines the relative weight of the tail reduction in the field of view and the collection field stop function uniformity,
L < / RTI > defines a viewing aperture size. A system for performing optical metrology,
A stage configured to support a sample;
At least one illumination source configured to provide illumination along an illumination path to illuminate a surface of the sample;
An apodizer disposed in a pupil plane of the illumination path and configured to apodize illumination directed along the illumination path;
An illumination field stop disposed along the illumination path and configured to block a portion of the illumination directed along the illumination path from striking the surface of the sample;
At least one detector configured to detect a portion of the scattered, reflected, or copied illumination from the surface of the sample along a collection path;
An apodized collective field of view aperture configured to apodize illumination directed along the collecting path and to block a portion of the directed illumination along the collecting path, apodized collection filed stop);
A computing system communicatively coupled to the at least one detector and configured to determine at least one spatial attribute of the sample based on a portion of the detected illumination. 25. The system of claim 24, further comprising an illumination scanner disposed along the illumination path and configured to scan a surface of the sample with at least a portion of the apodized illumination. 27. The system of claim 26, wherein the illumination scanner is further configured to direct illumination, scattered, reflected or copied from a surface of the sample along the collection path, to the at least one detector. 25. The system of claim 24, wherein the illumination field diaphragm comprises an apodized field stop. 25. The system of claim 24, wherein the at least one illumination source comprises a coherent illumination source. 25. The method of claim 24, wherein the apodization profile of the apodizer is expressed by the following equation

, Where < RTI ID = 0.0 >
F (p (k)) is a cost function,
p (k) is the pupil apodizer profile,
x ₀ defines the target range of the sample,
k ₀ defines a target range of the pupil plane,
lambda ₁ defines the relative weight of the tail reduction in the field plane and pupil function uniformity,
And NA defines a pupil aperture. 26. The method of claim 24, wherein the apodization profile of the apodized collection field aperture has the following formula:

, Where < RTI ID = 0.0 >
F (p (x)) is a cost function,
p (x) is the field stop apodizer profile,
x ₀ defines the target range of the sample,
k ₀ defines a target range of the pupil plane,
lambda ₂ defines the relative weight of tail reduction in the field of view and collection field stop function uniformity,
L < / RTI > defines a viewing aperture size.

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